Car Navigation Apparatus

ABSTRACT

A car navigation apparatus includes an intersection searching means  14  for searching for intersections in a vicinity of the current position of a vehicle from intersections which exist on a searched route and which exist between the current position and a destination, an intersection name outputting means  15  for outputting the names of the searched intersections, an intersection selecting means  17  for selecting an intersection from the intersection names outputted, an facility searching means  18  for searching for facilities which exist in a vicinity of the intersection selected through the map data, a facility name outputting means  19  for outputting the names of the searched facilities, a facility selecting means  20  for selecting a facility from the facility names outputted, and a facility information outputting means  21  for extracting facility information about the selected facility from the map data, and for outputting the facility information.

FIELD OF THE INVENTION

The present invention relates to a car navigation apparatus whichsearches for a route to a destination and carries out route guidance.More particularly, it relates to a technology for easily acquiringfacility information about facilities in the vicinity of an intersectionon the route which is searched for.

BACKGROUND OF THE INVENTION

Conventionally, a car navigation apparatus having a function ofdisplaying a list of the names of intersections either in the vicinityof a vehicle in which the car navigation apparatus is mounted or on asearched route while the vehicle is traveling along the searched routeis known. Since this car navigation apparatus aims at informing the userof intersections in the vicinity of the vehicle or on the route so as toguide the user to the destination safely, it only has either thefunction of displaying the list of the intersections, or a function ofdisplaying a map of an area including or intersection information aboutan intersection which is selected from the displayed intersection list(the intersection's name, the number of lanes of the intersection,etc.).

On the other hand, a car navigation apparatus usually has varioussurrounding facilities searching services, such as a vehicle positionsurrounding facilities searching service, a map point surroundingfacilities searching service, a place-of-arrival surrounding facilitiessearching service, and a route surrounding facilities searching service.However, there have been provided no car navigation apparatus having afunction of selecting a desired intersection from a list ofintersections on a searched route to perform a search for surroundingfacilities in the vicinity of the desired intersection.

Therefore, in order to search for surrounding facilities in the vicinityof a selected intersection, the user needs to cause the related art carnavigation apparatus to stop route guidance and display a map of an areaincluding the selected intersection on the screen, move a cursor to thedesired intersection on the map using a remote controller or a joystickto set a point to be searched, and, after that, cause the related artcar navigation apparatus to perform a search for surrounding facilitiesin the vicinity of the set point to be searched. This related art carnavigation apparatus thus makes the user have the trouble of moving thecursor to the specific point on the map, and this operation ofpositioning the cursor at the desired intersection on the map causes theuser to stare at the screen inevitably, thereby preventing the user fromdriving the vehicle. When the user can specify a point on the map bymanipulating a touch panel with a finger, he or she does not need tostare at the screen. However, a drawback is that when the vehicle iscurrently located in a large city, for example, and a very large numberof intersections are displayed on the screen, it is difficult for theuser to specify the desired intersection correctly.

Although a method of allowing the user to directly specify anintersection on a map for route guidance can be alternatively consideredas the method of specifying the intersection, when the map isautomatically scrolled around as the vehicle moves, when the desiredintersection exists in an edge of the screen display, when the desiredintersection does not exist in the screen display because of the scaleof the map, and when a large number of intersections exist in the screendisplay, it is difficult for the user to perform such an operation ofspecifying the desired intersection. Although a method of specifying anintersection by specifying a street which crosses the road along whichthe vehicle is currently traveling, and performing a search forsurrounding facilities in the vicinity of the specified intersection canbe also considered, it cannot be used when no name is given to thestreet and when the user does know the name of the street.

Patent reference 1 discloses, as a related technology, aroute-to-be-traveled guidance apparatus for displaying both the currentposition on a map of a vehicle in which the guidance apparatus ismounted and the names of a plurality of intersections on a guidanceroute and in the vicinity of the current position on a display. Thisroute-to-be-traveled guidance apparatus reads the names of a pluralityof intersections on the guidance route and in the vicinity of thecurrent position, which are selected through route searching, from aCD-ROM 7, and collectively displays the names of the plurality ofintersections on a liquid crystal display on which a map, a markindicating the vehicle, etc. are displayed. As a result, the user cangrasp information about intersections located in a wide area surroundingthe current position of the vehicle.

Patent reference 2 discloses a guidance route searching method which anavigation apparatus uses to search for a guidance route passing throughroads which are to the user's liking and are extending to a destination.In accordance with this guidance route searching method, a first routefrom the place of departure to the destination is searched for, andintersections on the route are displayed in the form of a list. When theuser selects a desired intersection from among the intersections on thefirst route, and specifies a traveling direction in which the vehicleshould go out of the desired intersection, the method reduces the linkcost of the road which is extending in the specified direction from theselected intersection, and searches for a route (i.e., a second route)extending from the intersection to the destination. The method thencombines a part of the first route, which is extending from the place ofdeparture to the desired intersection, and the second route into aguidance route.

Patent reference 3 discloses a navigation apparatus which can provideregulations, congestion information, etc. at an appropriate timing, andwhich enables the user to grasp the conditions of intersections inadvance by displaying information about the intersections in advance,for example. This navigation apparatus includes a traffic informationdetecting means, such as a VICS receiver, for detecting trafficinformation which exists on a road along which the vehicle shouldtravel, and an intersection information providing means for, when thetraffic information detecting means detects traffic information whichexists on a road, providing detailed information about the names ofintersections located on this side of a location associated with thetraffic information which exists on the road along which the vehicleshould travel, the distance to each of the intersections, marksrespectively indicating the intersections, an intersection map, a lanemap, a road map, etc.

[Patent reference 1] JP, 9-133541,A[Patent reference 2] JP, 2003-121186,A[Patent reference 3] JP, 2002-286476,A

Related art car navigation apparatus have some surrounding facilitiessearching services, such as a vehicle position surrounding facilitiessearching service, a map point surrounding facilities searching service,a place-of-arrival surrounding facilities searching service, and a routesurrounding facilities searching service, as mentioned above. However,since each of these facilities searching services has an advantage and adisadvantage, they are used so as to be complementary to one another.For example, when the user desires to search for a gas station in ahurry, the related art car navigation apparatus can perform a vehicleposition surrounding facilities search. However, there is a possibilitythat gas stations which exist in a direction opposite to the travelingdirection of the vehicle are also searched for in this vehicle positionsurrounding facilities search. In such a case, since only gas stationswhich exist in the traveling direction can be searched for when a routesurrounding facilities search is performed, the disadvantage of thevehicle position surrounding facilities search can be removed.

However, since all locations on the route become a target to be searchedin the route surrounding facilities search, unnecessary gas stations inthe vicinity of the point of arrival are searched for, and therefore theroute surrounding facilities search takes relatively long time.Therefore, it is necessary to take measures, such as a measure ofrestricting the area to be searched or the number of facilities to besearched. Under such conditions, the related art car navigationapparatus needs to further have a function of complementing the routesurrounding facilities searching function. That is, the related art carnavigation apparatus needs to have a facilities searching function ofrestricting the target to be searched to facilities which exist in thetraveling direction of the vehicle and in the vicinity of the vehicle,making the area to be searched substantially wide, and being able tosearch for the facilities in a short time.

In addition, since there is a high possibility that the user performsmistaken operations under conditions that the use needs to cause therelated art car navigation apparatus to perform a search for facilitiesin a hurry, the number of times that the user performs operations tocause the related art car navigation apparatus to perform a search forfacilities has to be reduced as much as possible to simplify theprocedure, and the length of time that the user stares at an operationscreen display for the procedure has to be reduced. Furthermore, afunction of properly searching for information which the user desires tohave and providing it for the user so that the user does not need toredo the operations for searching is needed.

The present invention is made in order to meet the above-mentionedrequests, and it is therefore an object of the present invention toprovide a car navigation apparatus which can provide information aboutfacilities in the vicinity of an intersection quickly according to auser's simple operations.

DISCLOSURE OF THE INVENTION

In order to solve the above-mentioned problems, a car navigationapparatus in accordance with the present invention includes: a map dataacquisition means for acquiring map data including road data,intersection information, and facility information; a current positiondetection means for detecting a current position of a car; a routesearching means for searching for a route to a destination based on themap data acquired by said map data acquisition means; an intersectionsearching means for searching an intersection in a vicinity of thecurrent position from among intersections which are located on the routesearched for by said route searching means and which exists between thecurrent position detected by said current position detection means andthe destination; an intersection name outputting means for outputtingthe intersection's name given to the intersection searched for by saidintersection searching means; an intersection selecting means forselecting the intersection by specifying the intersection's nameoutputted by said intersection name outputting means; an facilitysearching means for searching for a facility which exists in a vicinityof the intersection selected by said intersection selecting meansthrough the map data acquired by said map data acquisition means; afacility name outputting means for outputting the facility's name givento the facility searched for by said facility searching means; afacility selecting means for selecting the facility by specifying thefacility's name outputted by said facility name outputting means; and afacility information outputting means for extracting facilityinformation about the facility selected by said facility selecting meansfrom the map data acquired by said map data acquisition means, and foroutputting the facility information.

Thus, the car navigation apparatus can output the names of intersectionswhich exist between the current position and the destination so that theuser can simply specify one of these outputted intersection names tomake the car navigation apparatus search for facilities which exist inthe vicinity of the selected intersection and output the names of thefacilities. Therefore, the user can make the car navigation apparatusprovide information about facilities in the vicinity of the selectedintersection by performing a simple operation. Since the car navigationapparatus sets, as a target to be searched, intersections which existbetween the current position and the destination, the car navigationapparatus provides an advantage of being able to promptly provideinformation about desired facilities for the user in a short time.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing the structure of a car navigationapparatus according to embodiment 1 of the present invention;

FIG. 2 is a block diagram showing the functional structure of a controlunit shown in FIG. 1;

FIG. 3 shows an example of a setting screen display of a list ofintersections which is used in the car navigation apparatus according toembodiment 1 of the present invention;

FIG. 4 shows an example of a setting screen display for setting facilitysearching conditions which are used in the car navigation apparatusaccording to embodiment 1 of the present invention;

FIG. 5 shows an example of a setting screen display for setting thedetails of the types of facilities which are used in the car navigationapparatus according to embodiment 1 of the present invention;

FIG. 6 is a flow chart showing intersection searching processing carriedout by the car navigation apparatus according to embodiment 1 of thepresent invention;

FIG. 7 is a flowchart showing facility searching processing carried outby the car navigation apparatus according to embodiment 1 of the presentinvention;

FIG. 8 is a diagram showing an example of a screen display of a list ofintersections in the car navigation apparatus according to embodiment 1of the present invention;

FIG. 9 is a diagram showing another example of the screen display of alist of intersections in the car navigation apparatus according toembodiment 1 of the present invention;

FIG. 10 is a diagram showing an example of a screen display of a list offacilities in the car navigation apparatus according to embodiment 1 ofthe present invention;

FIG. 11 is a diagram showing an example of a screen display of detailedinformation about facilities in the car navigation apparatus accordingto embodiment 1 of the present invention; and

FIG. 12 is a diagram showing another example of the screen display ofdetailed information about facilities in the car navigation apparatusaccording to embodiment 1 of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereafter, in order to explain this invention in greater detail, thepreferred embodiments of the present invention will be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 is a block diagram showing the structure of a car navigationapparatus according to embodiment 1 of the present invention. This carnavigation apparatus is provided with a disk driving unit 1, a GPSreceiver 2, a self-contained navigation sensor 3, an operation unit 4, acontrol unit 5, a display unit 6, a voice output unit 7, a voice inputunit 8, and a communication control unit 9.

The disk driving unit 1 drives a DVD-ROM or CD-ROM to read map data froma map database formed in this medium. Facility information aboutfacilities which are classified, for example, into some categories, suchas a shopping center category, a gas station category, and a restaurantcategory, as well as road information, is included in the map data. Themap data read by this disk driving unit 1 are sent to the control unit5.

The GPS receiver 2 determines the current position (i.e., the latitudeand longitude) of a vehicle in which the car navigation apparatus ismounted based on GPS signals acquired by receiving electric waves sentfrom the GPS satellites. GPS data indicating the current position of thevehicle determined by this GPS receiver 2 is sent to the control unit 5.

The self-contained navigation sensor 3 includes an angle sensor and avelocity sensor (neither of these sensors are shown in the figure). Theangle sensor detects the traveling direction of the vehicle in which thecar navigation apparatus is mounted. The traveling direction detected bythis angle sensor is sent to the control unit 5 as direction data. Thevelocity sensor measures the number of pulses which are generated everytime when the vehicle in which the car navigation apparatus is mountedtravels a constant distance. The number of pulses measured by thisvelocity sensor is sent to the control unit 5 as velocity data.

The operation unit 4 is used in order for the user to manipulate the carnavigation apparatus. This operation unit 4 receives operationinformation sent via, e.g., infrared radiation from a remote controller,generates an operation command corresponding to this received operationinformation, and sends it to the control unit 5. The operation unit 4can be constructed of a touch panel placed on the screen of the displayunit 6. In this case, the touch panel generates an operation commandcorresponding to a position thereof which the user touches, and sends itto the control unit 5. The operation unit 4 can be alternativelyconstructed of a manual operation button, such as a joystick or a crossbutton, which are disposed on a front surface of the car navigationapparatus.

The display unit 6 is constructed of, for example, a liquid crystaldisplay, and displays a map, a list of intersections (or junctions), orthe like according to display data from the control unit 5. The voiceoutput unit 7 is constructed of, for example, a speaker or the like, andcarries out guidance by voice according to voice data from the controlunit 5. The voice input unit 8 is constructed of, for example, amicrophone, converts a voice into a sound signal, and sends it to thecontrol unit 5 as voice data. The voice data delivered from this voiceinput unit 8 is also used to manipulate the car navigation apparatususing a voice recognition means (not shown) disposed within the controlunit 5. The communication control unit 9 is used in order to controlcommunications between the car navigation apparatus and equipmentlocated outside the car navigation apparatus.

The control unit 5 controls the whole of this car navigation apparatus.This control unit 5 includes a central processing unit (referred to as“CPU” from here on) 5 a, a storage-type memory 5 b, a temporary memory 5c, and a hard disk drive unit (referred to as “HDD” from here on) 5 d.The CPU 5 a carries out various processes and a process of receiving anddelivering data. The storage-type memory 5 b consists of, for example,an EEPROM, and stores the current position of the vehicle, adestination, correction values used for the velocity sensor and anglesensor, points on the map which are registered by the user, componentsetting information for tailoring the settings of some components to theuser's liking, etc. The temporary memory 5 c consists of, for example, aDRAM, and is used in order to store various pieces of informationtemporarily. The HDD 5 d stores the same map database as that stored inthe DVD-ROM, CD-ROM, or the like which is driven by the disk drivingunit 1.

FIG. 2 is a block diagram showing the functional structure of thecontrol unit 5. This control unit 5 is provided with a current positiondetecting means 10, a map data acquiring means 11, a route searchingmeans 12, an intersection searching condition setting means 13, anintersection searching means 14, an intersection name outputting means15, a facility searching condition setting means 16, an intersectionselecting means 17, a facility searching means 18, a facility nameoutputting means 19, a facility selecting means 20, a facilityinformation outputting means 21, and an expected-route-to-be-followeddetermining means 22.

The current position detecting means 10 carries out a predeterminedcalculation based on the GPS data sent from the GPS receiver 2, thedirection data sent from the angle sensor which constitutes theself-contained navigation sensor 3, and the velocity data sent from thevelocity sensor which constitutes the self-contained navigation sensor3, so as to detect the current position of the vehicle in which the carnavigation apparatus is mounted. Current position data indicating thecurrent position of the vehicle detected by this current positiondetecting means 10 is sent to the route searching means 12 andintersection searching means 14.

The map data acquiring means 11 acquires map data from the map databaseformed in the DVD-ROM or CD-ROM which is mounted into the disk drivingunit 1, or the HDD 5 d. The map data acquired by this map data acquiringmeans 11 is sent to the route searching means 12, intersection searchingmeans 14, facility searching means 18, and facility informationoutputting means 21. The route searching means 12 searches for a routeextending from the position specified by the current position data sentfrom the current position detecting means 10 to a position specified bythe destination data delivered from the operation unit 4 based on themap data acquired by the map data acquiring means 11. Guidance routedata showing the route which is searched for by this route searchingmeans 12 is sent to the intersection searching means 14.

The intersection searching condition setting means 13 sets intersectionsearching conditions which are used for specifying intersections whichare a target to be searched. To be more specific, the intersectionsearching condition setting means sets conditions to be imposed onintersections which are a target to be searched, for example, the widthsof each road crossing the route, the number of lanes of each roadcrossing the route, and the type of each road crossing the route, suchas a national road or prefectural road, at each intersection accordingto the user's operation of the operation unit 4. The intersectionsearching conditions set by this intersection searching conditionsetting means 13 are sent to the intersection searching means 14. Theintersection searching means 14 searches for intersections in thevicinity of the current position of the vehicle from among intersectionswhich are located on the route shown by the guidance route data sentfrom the route searching means 12, and which exist between the currentposition detected by the current position detecting means 10 and thedestination based on the map data acquired by the map data acquiringmeans 11 and according to the intersection searching conditions set bythe intersection search condition setting means 13. The names of theintersections searched for by this intersection searching means 14 aresent to the intersection name outputting means 15.

The intersection name outputting means 15 sends the names of some of theintersections, which are located in the most vicinity of the vehicle, tothe display unit 6. As a result, as shown in, for example, FIG. 8, someintersection names are displayed on a left half of the screen of thedisplay unit 6. The facility searching condition setting means 16 setsfacility searching conditions which are used for specifying facilitieswhich are a target to be searched. To be more specific, the facilitysearching condition setting means sets a distance from a selectedintersection to facilities which are the target to be searched, or atraveling time required for the vehicle to travel from the selectedintersection to the target facilities, a restriction imposed ondirections in which the vehicle can go out of the intersection (e.g.,only going straight and left turn, only going straight and right turn,highway, or prefectural road), the type of the target facilities (hotel,restaurant, gas station, or the like), and functions which the targetfacilities should have (existence of parking lot or the like), accordingto the user's operation of the operation unit 4. The facility searchingconditions set by this facility searching condition setting means 16 aresent to the facility searching means 18.

The intersection selecting means 17 selects an intersection byspecifying the name of the intersection which is displayed on thedisplay unit 6 by the intersection name outputting means 15 according tothe user's operation of the operation unit 4. Data showing theintersection selected by this intersection selecting means 17 is sent tothe facility searching means 18. The facility searching means 18searches for surrounding facilities in the vicinity of the intersectionselected by the intersection selecting means 17 based on the map dataacquired by the map data acquiring means 11 according to the facilitysearching conditions set by the facility searching condition settingmeans 16. Information about the facilities searched for by this facilitysearching means 18 is sent to the facility name outputting means 19.

The facility name outputting means 19 sends the names of the searchedfacilities to the display unit 6. As a result, as shown in, for example,FIG. 9, the names of the facilities are displayed on the left half ofthe screen of the display unit 6 in the form of a list. The facilityselecting means 20 selects a facility from the facilities by specifyingthe name of the facility which is displayed on the display unit 6 by thefacility name outputting means 19 according to the user's operation ofthe operation unit 4. Data showing the facility selected by thisfacility selecting means 20 is sent to the facility informationoutputting means 21. The facility information outputting means 21extracts detailed information about the selected facility from the mapdata acquired by the map data acquiring means 11, and sends it to thedisplay unit 6. As a result, as shown in, for example, FIG. 11, thedetailed information about the selected facility is displayed on theleft half of the screen of the display unit 6.

The expected-route-to-be-followed determining means 22 calculates a linkcost based on the direction data showing the traveling direction, whichis acquired from the angle sensor which constitutes the self-containednavigation sensor 3, and the width, number of lanes, etc. of each roadwhich crosses the road along which the vehicle is traveling, which areincluded in the map data acquired by the map data acquiring means 11,and determines a route having the lowest link cost as an expected routeto be followed. The link cost of a route is a value which is multipliedby a constant which varies according to the width and type of each roadon the route, the number of times that the vehicle will make a right orleft turn when traveling the route, etc. for route searching, and isevaluated in order to optimize the guidance route. Data indicating theexpected route to be followed determined by theexpected-route-to-be-followed determining means 22 is sent to theintersection searching means 14.

Next, the operation of the car navigation apparatus according toembodiment 1 of the present invention which is constructed as mentionedabove will be explained.

The user first sets conditions, such as a searching condition which issuited to the user's liking, and a route guidance condition beforesetting a destination and causing the car navigation apparatus to startroute guidance. In other words, when performing a search for facilitiesin the vicinity of an intersection on the route, since the carnavigation apparatus needs to display a list of intersections whilecarrying out the route guidance, the user performs a predeterminedoperation on the operation unit 4 to cause the car navigation to displaya setting screen for display of intersection list as shown in FIG. 3.The user then sets “Maneuver List” to ON. As a result, the display unitis placed in a state where the display of an intersection list isactivated, the intersection list is displayed on the left half of thescreen of the display unit 6, as shown in FIG. 9, and a route guidancemap is displayed on the right half of the screen. In the setting screenfor display of intersection list, in order to obtain a list offacilities needed for the user, the user is allowed to specifyconditions imposed on intersections to be searched, for example, “thetypes of crossing roads”, “national road or city street intersection”,“highway intersection”, “intersection having two or more lanes”, etc.Information stored as road attributes or intersection attributesincluded in the map data can be used as these conditions.

When setting facility searching conditions, the user performs apredetermined operation on the operation unit 4 so as to cause the carnavigation apparatus to generate a setting screen display, as shown inFIG. 4, for setting of the facility searching conditions. In this screendisplay, the user can set a distance from the intersection to facilitiesto be searched or a traveling time required for the vehicle to travelfrom the selected intersection to the target facilities, existence ofparking lots in the target facilities, restrictions on the entry of thevehicle into the target facilities indicating whether the vehicle easilyarrives at the facilities, etc. When setting a distance from theintersection to the facilities to be searched, the user specifies thedistance from the intersection which the user selects for a search forfacilities. When the user sets a traveling time required for the vehicleto travel from the intersection to the facilities to be searched, thetraveling time is converted into a distance using the average velocityof the vehicle. The average velocity is defined in advance as aconstant, or is calculated based on the velocity data acquired from thevelocity sensor which constitutes the self-contained navigation sensor3. As facilities which the vehicle can easily reach (i.e., restrictionson the entry of the vehicle into facilities), the user specifiesfacilities which the vehicle can reach after preferably moving straightforward or making a left turn (or moving straight forward or making aright turn) with respect to the traveling direction of the vehicle. Inthis case, the car navigation apparatus carries out a search forfacilities using route searching information, such as a link cost, and anode cost, which is included in the map data.

When the user desires to restrict facilities which are the target to besearched, he or she manipulates a “Select” button of the screen shown inFIG. 4 so as to cause the car navigation apparatus to generate a screendisplay for setting of the details of the types of facilities as shownin FIG. 5. The user then specifies facilities which are the target to besearched. FIG. 5 shows an example in which airports (AIRPORT) and gasstations (AUTOMOBILE CLUB) are selected as the target facilities. Theconditions set as mentioned above are registered into the storage-typememory 5 b. Thus, since only facilities of the registered types aredisplayed in the list of searched facilities after a search forfacilities is carried out, the user can recognize only the displayed,needed list of facilities.

When the settings mentioned above are completed, the control unit 5carries out intersection searching processing shown in a flow chart ofFIG. 6, and facility searching processing shown in a flow chart of FIG.7.

First, the control unit checks to see whether guidance route dataalready exists (in step ST10). In other words, the control unit checksto see whether a route search has been made by the route searching means12. When determining that no guidance route data exists (any destinationis not specified), the control unit then checks to see whether or not adestination is specified (in step ST11). When determining that adestination is specified, the control unit carries out a determinationof a guidance route, i.e., a search for a route to the destination (instep ST12). After that, the control unit advances the sequence to stepST14. When, in above-mentioned step ST11, determining that anydestination is not specified, the control unit determines an expectedroute to be followed (in step ST13). In other words, theexpected-route-to-be-followed determining means 22 determines anexpected route to be followed, and sends expected route to be followeddata about the expected route to be followed to the intersectionsearching means 14. After that, the control unit advances the sequenceto step ST14. When, in above-mentioned step ST10, determining thatguidance route data exists, the control unit advances the sequence tostep ST14.

The control unit, in step ST14, acquires intersections which exist ineither the route indicated by the guidance route data or the expectedroute to be followed indicated by the expected route to be followeddata. The control unit then creates a list of intersections from theacquired intersections. The intersection list includes the names of someintersections in the vicinity of the current position of the vehicle,which are listed in order that they will be passed through. The controlunit then acquires the vehicle position information about the currentposition of the vehicle (in step ST15). In other words, the intersectionsearching means 14 acquires the current position data from the currentposition detecting means 10. The control unit then checks to see whetherthe vehicle has strayed from the guidance route (in step ST16). Thecontrol unit carries out this process by checking to see whether thecurrent position indicated by the current position data acquired in stepST15 exists on the guidance route. When determining that the vehicle hasstrayed from the guidance route, the control unit carries out are-determination of the guidance route (in step ST17). After that, thecontrol unit advances the sequence to step ST18.

When, in above-mentioned step ST16, determining that the vehicle has notstrayed from the guidance route, the control unit checks to see whetherthe vehicle has passed through the nearest intersection (in step ST21).When determining that the vehicle has passed through the nearestintersection, the control unit advances the sequence to step ST18. Onthe other hand, when determining that the vehicle has not passed throughthe nearest intersection yet, the control unit advances the sequence tostep ST19.

The control unit, in step ST18, updates the intersection list. Thecontrol unit then updates the display of the map and intersection list(in step ST19). The control unit also carries out a search forfacilities in the vicinity of an intersection (in step ST20). In thesearch for facilities in the vicinity of an intersection, the controlunit searches for surrounding facilities in the vicinity of anintersection specified by the user, as will be mentioned later indetail. After that, the control unit returns the sequence to step ST15in which it repeats the above-mentioned processing.

With the above-mentioned processing, the control unit always displaysthe list of nearby intersections on the left half of the screen of thedisplay unit 6 which is providing route guidance, and also displays amap for route guidance which contains a mark indicating the currentposition of the vehicle on the right half of the screen of the displayunit, as shown in FIG. 8. Then, when the vehicle has passed through thenearest intersection or when the vehicle has strayed from the guidanceroute and a re-determination of the guidance route is carried out, thecontrol unit updates the list of intersections. Every time when thecurrent position of the vehicle changes, the control unit updates themap containing the current position mark indicating the current positionof the vehicle. In the example of the screen display shown in FIG. 3,the screen is divided into two portions and the list of intersections isdisplayed on the left-hand side of the screen. This screen display isshown as an example, and the layout of the number of screen portions,the number of intersections included in the intersection list, and so onare arbitrary as long as the map for route guidance and the intersectionlist are simultaneously displayed on the screen.

Next, the details of the process of searching for facilities in thevicinity of an intersection, which is performed in above-mentioned stepST20, will be explained with reference to the flow chart of FIG. 7.

In this facility searching processing, the control unit checks to seewhether or not an intersection is selected first (in step ST30). As anintersection selecting method, a method of allowing the user to selectan intersection's name from the list of intersections by using a remotecontroller, a joystick, a cross button, speech recognition, or the like,or to select an intersection by pushing a predetermined button, such asan intersection 1 button or intersection 2 button, or a method ofallowing the user to select a desired intersection by touching it from ashown list of intersections when the operation unit 4 consists of atouch panel can be adopted.

When, in step ST30, determining that any intersection is not selected,the control unit returns the sequence from this facility searchingprocessing to the processing shown in the flow chart of FIG. 6 On theother hand, when determining that an intersection is selected, thecontrol unit acquires the searching conditions (in step ST31). In otherwords, the control unit acquires the facility searching conditions setby the facility searching condition setting means 16. The control unitthen carries out a search for surrounding facilities (in step ST32). Inother words, the facility searching means 18 searches for surroundingfacilities in the vicinity of the intersection selected, in step ST30,by the intersection selecting means 17 based on the map data acquired bythe map data acquiring means 11 from the map database, and according tothe facility searching conditions set, in step ST32, by the facilitysearching condition setting means 16. The range to be searched is anarea at a constant distance from the position (i.e., the latitude andlongitude) of the selected intersection.

The control unit then checks to see whether facilities which satisfy thefacility searching conditions exist (in step ST33). When thendetermining that no facilities which satisfy the facility searchingconditions exist, the control unit displays a surrounding map of an areaincluding the intersection or a message indicating that no facilitieswhich satisfy the facility searching conditions exist (in step ST34),and ends the facility searching processing. After that, the control unitreturns the sequence to the processing shown in the flow chart of FIG.6. On the other hand, when, in step ST33, determining that facilitieswhich satisfy the facility searching conditions exist, the control unitdisplays a list of the facilities and a surrounding map (in step ST35).In other words, the control unit generates a list of the names of thefacilities searched in step ST32, combines this generated list of thenames of the facilities and the surrounding map of the area includingthe intersection which is displayed when the selection of theintersection is carried out by using the facility name outputting means19, as shown in FIG. 9, and displays the combined image on the displayunit 6. Although the control unit is so constructed as to, in step ST35,display the facility namelist and the surrounding map of theintersection, as shown in FIG. 9, the control unit can alternativelydisplay the facility namelist and the map for route guidance, as shownin FIG. 10. In this case, the user can set in advance whether thecontrol unit will display either the combination of a facility namelistand a surrounding map of the intersection, as shown in FIG. 9, or thecombination of a facility namelist and a map for route guidance, asshown in FIG. 10, so that the control unit can display either of thecombinations according to the setting in step ST35.

The control unit then checks to see whether or not one facility's nameis selected from the facility list as shown in FIG. 9 (in step ST36).When determining that one facility is selected, the control unitdisplays detailed information about the selected facility (in stepST37). In other words, the facility information outputting means 21extracts the detailed information about the selected facility out of themap data acquired from the map database by the map data acquiring means11, and sends it to the display unit 6. The control unit thus displaysthe detailed information about the facility on the left half of thescreen of the display unit 6, as shown, for example, in FIG. 11. In thiscase, the control unit can alternatively display the detailedinformation about the facility on the whole screen of the display unit6, as shown in FIG. 12. An “Itinerary” button and a “Back” button areformed in the screen in which the detailed information about thefacility is shown. The “Itinerary” button is used in order for the userto instruct the car navigation apparatus to register the facilitycurrently being displayed on the display unit 6 as a via point or thedestination. The “Back” button is used in order for the user to instructthe car navigation apparatus to switch to the initial screen in whichthe map for route guidance is shown.

The control unit then checks to see whether or not a registrationinstruction is provided (in step ST38). In other words, the control unitchecks to see whether or not the “Itinerary” button is pushed. Whendetermining that the registration instruction is provided, that is, whendetermining that the “Itinerary” button is pushed, the control unitregisters, as a via point (or the destination), the selected facilityinto the storage-type memory 5 b (in step ST39). After that, the controlunit returns the sequence to the processing shown in the flow chart ofFIG. 6. On the other hand, when, in step ST38, determining that noregistration instruction is provided, that is, when determining that the“Back” button is pushed, the control unit returns the sequence to theprocessing shown in the flow chart of FIG. 6. As a result, the displayunit returns to the initial screen in which the list of intersectionsand the map for route guidance are shown. Also when no facility name isselected in above-mentioned step ST36, the control unit returns to theprocessing shown in the flow chart of FIG. 6.

As previously explained, the car navigation apparatus according toembodiment 1 of the present invention does not need to switch from ascreen display for route guidance to another screen display in order tocarry out a search for facilities, and, by simply allowing the user tospecify the name of an intersection which exists between the currentposition and the destination and which is currently shown in the displayunit 6 by using the operation unit 4, searches for and outputsfacilities which exist in the vicinity of the intersection. Therefore,the car navigation apparatus can provide information about facilities inthe vicinity of a selected intersection in response to the user's simpleoperations. As a result, the present invention offers a useful advantagefrom a safe driving standpoint. In addition, since only intersectionswhich exist on either a guidance route extending from the currentposition of the vehicle to the destination or an expected route to befollowed which is extending from the current position in the directionin which the vehicle is headed are defined as the target to be searched,the car navigation apparatus can promptly provide desired facilities ina short time.

Since the user is allowed to specify the types of a road which crossesthe route, such as a national road or city street, at each targetintersection to be searched, the number of lanes of a road which crossesthe route at each target intersection to be searched, or searchingconditions that a higher priority is given to going-straight andleft-turn than to right-turn, and facility searching conditions that ahigher priority is given to facilities with a parking lot entrancefacing a road included in the route, the car navigation apparatus caneasily perform a search for facilities which the user desires.

Since the car navigation apparatus allows the user to use a speechrecognition function or a touch panel in order to perform various kindsof inputs, the car navigation apparatus can perform a search forfacilities more easily. In addition, since the car navigation apparatusallows the user to specify the facility searching conditions set forsearching surrounding facilities in advance, the car navigationapparatus can exactly provide information which the user desires to theuser.

INDUSTRIAL APPLICABILITY

As mentioned above, the car navigation apparatus in accordance with thepresent invention is suitable for searching facilities in the vicinityof a target intersection.

1. A car navigation apparatus comprising: a map data acquiring means foracquiring map data including road data, intersection information, andfacility information; a current position detecting means for detecting acurrent position of a car; a route searching means for searching for aroute to a destination based on the map data acquired by said map dataacquiring means; an intersection searching means for searchingintersections in a vicinity of the current position from amongintersections which exist on the route searched by said route searchingmeans and which exists between the current position detected by saidcurrent position detecting means and the destination; an intersectionname outputting means for outputting intersection names given to theintersections searched by said intersection searching means; anintersection selecting means for selecting an intersection by specifyingan intersection name outputted by said intersection name outputtingmeans; a facility searching means for searching for facilities whichexist in a vicinity of the intersection selected by said intersectionselecting means through the map data acquired by said map data acquiringmeans; a facility name outputting means for outputting facility namesgiven to the facilities searched by said facility searching means; afacility selecting means for selecting a facility by specifying afacility name outputted by said facility name outputting means; and afacility information outputting means for extracting facilityinformation about the facility selected by said facility selecting meansfrom the map data acquired by said map data acquiring means, and foroutputting the facility information.
 2. The car navigation apparatusaccording to claim 1, characterized in that said apparatus includes afacility searching condition setting means for setting facilitysearching conditions for specifying facilities which are a target to besearched, and the facility searching means searches for facilities whichexist in a vicinity of the intersection selected by the intersectionselecting means from the map data acquired by said map data acquiringmeans according to the facility searching conditions set by saidfacility searching condition setting means.
 3. The car navigationapparatus according to claim 2, characterized in that the facilitysearching conditions set by the searching condition setting meansinclude a distance from the intersection selected by the intersectionselecting means or a traveling time required to travel from theintersection.
 4. The car navigation apparatus according to claim 2,characterized in that the facility searching conditions set by thesearching condition setting means include a restriction imposed ondirections in which the car can go out of the intersection selected bythe intersection selecting means.
 5. The car navigation apparatusaccording to claim 2, characterized in that the facility searchingconditions set by the searching condition setting means include types offacilities or functions provided by facilities.
 6. The car navigationapparatus according to claim 1, characterized in that the intersectionselecting means and the facility selecting means are provided with akey, a remote controller, a touch panel, or a voice recognition meansfor specifying an intersection name outputted by the facility nameoutputting means and a facility name outputted by the facility nameoutputting means.
 7. The car navigation apparatus according to claim 1,characterized in that said apparatus has an intersection searchingcondition setting means for setting intersection search conditions forspecifying intersections which are a target to be searched, and theintersection searching means searches for intersections in a vicinity ofthe current position through intersections which exists on the routesearched by the route searching means and which exists between thecurrent position detected by the current position detecting and thedestination according to the intersection searching conditions set bysaid intersection searching condition setting means.
 8. The carnavigation apparatus according to claim 1, characterized in that saidapparatus includes an angle sensor for detecting a traveling directionof the car, and an expected-route-to-be-followed determining means fordetermining an expected route to be followed based on the travelingdirection detected by said angle sensor and the map data acquired by themap data acquiring means, and the intersection searching means searchesfor intersections in a vicinity of the current position throughintersections which exist on the expected route to be followeddetermined by said expected-route-to-be-followed determining means whenno route is searched for by the route searching means.